For anything you'd like to see added to Speeduino
User avatar
By pazi88
#41292
That kind of hardware solutions could be used of course, but if you start to mess with the hardware, why not upgrade directly to teensy or stm32F407 which have the necessary extra timers to do 8x8 sequential. Code should be there already but I haven't got my hands on to either one yet to actually test.

Regarding the 6x6 sequential using mega, the injection and ignition side using timers works great, but you need to choose if you wan't to have igntion or injection sequential. I also have that mentioned software trickery to run ignition sequentially with 3 timers, but I have only got it working like 95%. Tried many things but still there is always some combination that causes wrong behavior. So I can't say it's finished. For now the 6-cyl sequential injection and Wasted COP mode has worked great in 6x6 board design.
By Rocket
#41351
Well I think hardware like this is very cheap and simple, if it will work accurately, cylinder count will be not a problem, so any speeduino board with small additional board could control for example v12 engine. Vems ecu use i think atmega128 and everything is made in hardware and works well. Most better UC is 3.3V and I'm quite worry about of their resistance to noise. of course additional functions like can bus are very beneficial.
By Selim aksil
#43432
I was thinkn...if the speeduino can manage a 3 cylinder engine sequentially at a 120° firing pattern ,and as an m50 bmw engine is a balanced 2×3 cylinder with mirroring pistons...can't we use a 2 speeduino emu setup with a cps with 180° from the original one, the same goes for the cam position sensor another lambda sensor for the second bank, the first would manage pistons 1,3,2 and the second would manage pistons 6,4,5 and u'd determine the firing order in the programmation..i know it'd be a debacle, still a manageable solution that could lead to the goal,
What do u think ???
And has anyone tried it yet??
By pishta
#66977
Looked I to this for a slant 6 on MS2. Sequential sounds great but it was only developed to tighten emissions control at low RPMs and cold starts. After about 2100 rpm, any injector is going to be hitting a closed valve as it's not fast enough to inject its full duty cycle into an open valve. As noted, a hot valve will aid in atomization of the fuel and the valves are moving so fast there is almost no dead time on a intake valve unless it's at very low RPMs. Very high RPM motors generally fog the entire intake from a distance using a 2nd set of injectors, ie. F1 motors . That's an extreme but it highlights the theory of sequential vs fogging or on a simpler note, batch or even bank fire. Probably not worth the headache.
By runesm
#67111
pishta wrote: Thu Feb 01, 2024 8:50 pm Looked I to this for a slant 6 on MS2. Sequential sounds great but it was only developed to tighten emissions control at low RPMs and cold starts. After about 2100 rpm, any injector is going to be hitting a closed valve as it's not fast enough to inject its full duty cycle into an open valve. As noted, a hot valve will aid in atomization of the fuel and the valves are moving so fast there is almost no dead time on a intake valve unless it's at very low RPMs. Very high RPM motors generally fog the entire intake from a distance using a 2nd set of injectors, ie. F1 motors . That's an extreme but it highlights the theory of sequential vs fogging or on a simpler note, batch or even bank fire. Probably not worth the headache.
Thats not entirely true. You cannot hold it to a specific rpm as such. You can however somewhat (and only somewhat) tie it to injector duty cycle. And the bigger the injector, the more you can get within the opening time of the valve. Also, going above ~25% duty (1/4 of engine cycle time where the intake valve is open and has airflow), you still get the first 25% of the fuel into a moving airstream, and the rest stagnant on the backside of the intake valve.
By JHolland
#67112
pishta wrote: Thu Feb 01, 2024 8:50 pm Looked I to this for a slant 6 on MS2. Sequential sounds great but it was only developed to tighten emissions control at low RPMs and cold starts. After about 2100 rpm, any injector is going to be hitting a closed valve as it's not fast enough to inject its full duty cycle into an open valve. As noted, a hot valve will aid in atomization of the fuel and the valves are moving so fast there is almost no dead time on a intake valve unless it's at very low RPMs. Very high RPM motors generally fog the entire intake from a distance using a 2nd set of injectors, ie. F1 motors . That's an extreme but it highlights the theory of sequential vs fogging or on a simpler note, batch or even bank fire. Probably not worth the headache.
You shouldn't dismiss the advantages at low RPM as simply for emissions, you can get good improvements in idle control, particularly when you have a lot of cam overlap.
User avatar
By PSIG
#67120
Which is a good point, as improvements in efficiency directly translate to better performances, from stability, to emissions, power and economy. However, there are no hard rules, and gains can be small. So the question becomes your goals for the project, and if a certain function or use of it contributes to those goals, balanced with the added complexity.

For examples, some modern systems (Chrysler-Benz and others) use 2-injections per-cycle, in order to promote vaporization on the closed valve shot for higher efficiency. Likewise, GM purposely avoids injecting on an open valve in many schemes. The reasoning ranges from quite simple to very complex. We must consider the common assumption that sequential is "supposed to inject on an open valve" is often simply not true, limiting in vision and options, and consider the reasons why that might be a benefit.
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